Polyvinyl acetal resin sheets containing an alkyl carbamate and dibutyl phthalate



Patented Dec. 5, 1939 PATENT OFFICE POLYVINYL ACETAL RESIN SHEETS CON- TAINING AN ALKYL CARBAMATE AND DIBUTYL PHTHALATE Henry B. Smith and Donald R. Swan, Rochester, N. Y., assignors to Eastman Kodak Company, Rochester, N. Y., a corporation of New Jersey No Drawing. Application December 3, 1937, Serial No. 177,966

3 Claims.

This invention relates to plastic compositions, and more particularly to compositions comprising a polyvinyl acetal resin and a conditioning agent.

One object of this invention is to produce compositions of matter which may be made into permanently transparent, strong and fiexible sheets or films of desired thinness which are substantially waterproof, are unaffected by ordinary photographic fluids and possess the desired properties of a support for sensitive photographic coatings.

' Another object of our invention is to produce compositions of matter which can be made into sheets suitable for use in laminated, shatter-proof glass. Still another object is to produce compositions which can be rolled, extruded, molded or otherwise worked into relatively thick sheets and massive plastics. A further object is to produce compositions suitable for use in lacquers, artificial silk filaments, wrapping tissues and the like. Other objects will hereinafter appear.

We havediscovered that an alkyl carbamate selected from the group consisting of butyl carbamate and isoamyl carbamate is a useful conditioning agent for polyvinyl acetal resins, increasing the flexibility and toughness of polyvinyl acetal resin films, sheets or other objects or masses containing it.

For the manufacture of cast films or sheets, the polyvinyl acetal resin and butyl or isoamyl carbamate may be dissolved in. a suitable solvent or solvent mixture, such, for instance, as acetone, methanol, acetone-methanol mixtures, ethylene chloride-methanol mixtures, etc., about 300 to 500,

or more parts of the solvent or solvent mixture being used per 100 parts of the resin. From about 2 to 35 parts of butyl or isoamyl carbamate per 100 parts of resin may be employed, depending upon the nature of the resin and the purpose for which the sheets are to be used. Suitable proportions of butyl or isoamyl carbamate for any 1 resin and any purpose may be readily determined by experiment. For the manufacture of sheets suitable for photographic film base, from 2 to 25 parts of butyl or isoamyl carbamate per 100 parts of'resin are suitable. The resin solution is cast as a sheet, solvent evaporated, and stripped from fcasting surface.

Butyl and isoamyl carbamates are not permanently compatible to the extent of 50 parts of the carbamate per 100 parts of certain of the polyvinyl acetal resin in sheets or films, a part of the with 100 parts of resin, an unusual and remarkable effect is obtained which we may call elasticizing. That is to say, a sheet of polyvinyl acetal resin containing about 40 or more parts,

- per 100 parts of polyvinyl acetal resin, of a mixture of 30-70% butyl or isoamyl carbamate and -30% dibutyl phthalate possesses the property which, in the rubber industry, is known as nerve; namely, the property of stretching to a considerable extent when tension is exerted upon it, and returning to its original dimensions when thetension is released. This property renders such sheets which we shall call rubbery sheets, particularly useful in the manufacture of shatterproof glass. The use of 40 parts of dibutyl phthalate alone with parts of polyvinyl acetal resin does not produce a rubbery sheet, except in the case of the polyvinyl butyraldehyde acetal resins. In fact, when 50 parts of dibutyl phthalate are used with 100 parts of a polyvinyl acetaldehyde acetalresin, the dibutyl phthalate tends to exude.

Sheets for use in laminated glass may be formed by casting, or may be made without the use of volatile solvent by extrusion, for example, in the manner set forth in application Serial No. 147,934 of John S. Kimble and Ernest C. Blackard, filed June 12,1937. For example, 40 or more parts of a mixture of 30-70% butyl or isoamyl carbamate and 70-30% dibutyl phthalate, and 100 parts of a polyvinyl acetal resin may be mixed in a suitable, jacketed mixer at a low temperature,

fan-

for example 10 C., and the mixture may then in the presence of an acetal condensation catalyst, e. g. a mineral acid.. These resins can also be prepared by simultaneously de-esterifying a polyvinyl aliphatic ester and reacting the deesterification productwith an aldehyde in the presence of a de-esterifying catalyst and acetalcondensation catalyst. Mineral acids are catalysts for both de-esterification and acetal formation. Among the polyvinyl acetal resins with which butyl and isoamyl carbamates are useful may be mentioned, as illustrative examples, the polyvinyl formaldehyde acetal resins, the polyvinyl acetaldehyde acetal resins, the polyvinyl formaldehyde acetaldehyde mixed acetal resins,

the polyvinyl butyraldehyde acetal resins, and the polyvinyl butyraldehyde acetaldehyde mixed acetal resins.

Examples of the preparation of polyvinyl formaldehyde acetal resins may be found in U. S.

- Patent 1,955,068, Examples 1, 4 and 5; in U; S.

Patent 2,036,092, Examples 1, 2, 3, '7 and 8; in British Patent 454,691, Examples 1, 2, 3, 4, 5, 6 and 7; in British Patent 404,279, Example 3; and in British Patent 436,072, Examples 1, 2, 3, 4, 5, 6 and 7. A further example of the preparation of a polyvinyl formaldehyde acetal resin is as follows:

25 lbs. of polyvinyl acetate, the viscosity of whose molar solution (86.08 g. per liter) in benzene was 45 centipoises, was dissolved in 75 lbs. of 70% acetic acid. To this solution were added 56 grams of hydroxylamine hydrochloride, for stabilizing the resin, 5.25 lbs. of trioxymethylene, and 6.25 lbs. of 35% HCl. The reaction mixture was allowed to stand for 5 days at 40 C., after which it was diluted with acetic acid. The resin was precipitated by pouring into cold water, washed, and dried. Analysis showed the resin to have an acetate group content equivalent to 10.6% by weight of polyvinyl acetate and ahydroxyl group content equivalent to 7.1 by weight of polyvinyl alcohol. The stabilization of poly- ,vinyl acetal resins by hydroxylamine is claimed in the application of Joseph B. Hale, Serial No. 149,916, filed June 23, 1937, now Patent No. 2,146,735.

Examples of the preparation of polyvinyl acetaldehyde acetal resins may be found in U. S. Patent 2,044,730, Example 1; U. S. Patent 1,955,068, Example 2; U. S. Patent 2,036,092, EX-

amples 4,'5.and 6; British Patent 466,598, Examples 1, 2, 3, 4 and 7; British Patent 404,279, Examples 1, 2, 4, 5, 6, 7 and 8; U. S. Patent 1,990,399; and French Patent 808,578, Examples 1, 2 and 3.

An additional example of the preparation of a polyvinyl acetaldehyde acetal resin is as follows:

100 lbs. of polyvinyl acetate, the viscosity of whose molar solution in benzene was 45 centipoises, was dissolved in 300 lbs. of 95% ethyl alcohol. To this solution were added 30 lbs. of paraldehyde and 25 lbs. of 35% HCl. The reaction mixture was allowed-to stand for. 4 daysat 40 0., after which it was diluted with ethyl althe resin to have an acetate group content equivalent to 2.1% by weight of polyvinyl acetate and a hydroxyl group content equivalent to 12.9% by weight of polyvinyl alcohol.

Examples of the preparation of polyvinyl formaldehyde acetaldehyde mixed acetal resins may be found in Britislf Patent 430,136, Examples 1, 2, 3, 4, 5 and 6; British Patent 445,565, Example 2; British Patent 465,873, Examples 1, 2, 3, 4, 5 and 6; French Patent 808,586, Examples 1, 2,. 3, 4, 5, 6, 12, 13, 14, 15, 16, 17, 18 and 19.

Additional examples of the preparation of polyvinyl formaldehyde acetaldehyde mixed acetal resins are given in the application of Ralph H. Talbot, Serial No. 85,960, filed June 18, 1936, as follows:

Example 1 100 parts (1.16 mol. calculated as monomeric vinyl acetate) of a polyvinyl acetate (45 centipoises), 100 parts of ethyl alcohol,- 180 parts of ethyl acetate, 34 parts (.77 mol. as monomeric acetaldehyde) of paracetaldehyde and 5.8 parts (.196 mol. as monomeric formaldehyde) of paraformaldehyde were placed in an enamelled vessel and brought into solution by stirring. When solution was complete, 10 parts of sulfuric acid (sp. g. 1.84) in 10 parts of water were added, and the mixture stirred. The mixture was maintained at a temperature of 40 C. for 144 hours. The contents of the vessel were then diluted with about two and a half volumes of acetone, and the mixture precipitated into water. The precipitated resin was washed free from impurities by repeated changes of cold water, and dried. The resin, when analyzed, gave a hydroxyl group content equivalent to about 6.4 per cent by weight of polyvinyl alcohol, an acetate group content equiv- 80.3 per cent by moles of polyvinyl acetaldehyde acetal. The resin was soluble in acetone to an extent which permitted coating a film or sheet from the resin.

Example? 50 parts (.58 mol. as monomer) of polyvinyl acetate (45 centipoises), 50 parts of ethyl alcohol, 90 parts of ethylacetate, 17 parts (.385 mol. as monomer) of paracetaldehyde, 2.9 parts (.098 mol. as monomer) of paraformaldehyde, 5 parts of sulfuric acid and 5 parts of water were treated as in Example 1 for 161 hours. The well washed and dried resin gave upon analysis a hydroxyl group content equivalent to about 9.6% by weight of polyvinyl alcohol, an acetate group content equivalent to about 4.1% by weight of polyvinyl acetate, a formaldehyde acetal group content equivalent to about 13.9 per cent by weight of polyvinyl formaldehyde acetal, and an acetaldehyde acetal group content equivalent to about 69.9 per cent of polyvinyl acetaldehyde acetal. The polyvinyl acetal portion of the resin was therefore made up of about 18.5 percent by moles of polyvinyl formaldehyde acetal and 81.5 per cent by moles of polyvinyl acetaldehyde acetal. The resin was soluble in acetone to anextent which permitted coating a film or sheet from the resin.

Example 3 1300 parts (15.1 mol. as monomer) of a polyvinyl acetate (45 centipoises) 1700 parts of ethyl acetate, 2250 parts of ethyl alcohol (95%) and 48 parts (1.57 mol. as monomer) of paraformaldehyde (trioxymethylene) were placed in a vessel equipped with a reflux condenser and a means of,

agitation, and the contents brought to a temperature of about 70 C. by means of steam heating. 182.25 parts of sulfuric acid (sp. g. 1.84) dissolved in 51.5 parts of water were added, and the whole The cake was cut into small pieces and repeatedly content equivalent to about 10.1 per cent by weight of polyvinyl alcohol, an acetate group content equivalent to about 3.2 per cent by weight of polyvinyl acetate, the remainder of the weight of the resin being polyvinyl acetal. The polyvinyl acetal portion of the resin was made up of about 80 percent by moles of polyvinyl acetaldehyde acetal and about percent by moles of polyvinyl formaldehyde acetal. The resin was not quite soluble in acetone, but could be made to dissolve by admixing small amounts of other solvents, such as alcohols, with the acetone.

Examples of the preparation of polyvinyl butyraldehyde acetal resins may be found in U. S. Patent; 2,044,730, Examples 2, 5 and 6; British Patent 466,598, Example 5; French Patent 813,303, Example 1; French Patent 813,514, Examples 1, 2, 3 and 4; and British Patent 459,878, Examples 1, 2, 5, 6, 7, 8, 9 and 10.

An example of the preparation of a polyvinyl butyraldehyde acetaldehyde mixed acetal resin is given in French Patent 813,303, Example 2.

What we claim as our invention and desire to be secured by Letters Patent 01 the United States is:

1. A transparent, rubbery sheet comprising 100 parts of a polyvinyl acetal resin and, as an elasticizer therefor, at least 40 parts, approximately, of a mixture consisting of -70% of an allqrl carbamate selected from the group consisting of butyl carbamate and isoamyl carbamate and 70-30% of dibutyl phthalate.

2. A transparent, rubbery sheet comprising 100 parts of a. polyvinyl acetal resin and, as an elasticizer therefor, at least parts, approximately, of a mixture consisting of 30-70% of butyl carbamate and -30% of dibutyl phthalate.

3. A transparent, rubbery sheet comprising parts of a polyvinyl acetal resin and, as an elasticizer therefor, at least 40 parts, approximately, of a mixture consisting of 30-70% of isoamyl carbamate and 70-30% of dibutyl phthalate.

HENRY B. SMITH. DONALD R. SWAN. 

